A light emitting diode (LED) is a semiconductor device that converts electricity into ultraviolet rays, infrared rays, or visible light using characteristics of a compound semiconductor. The LEDs have been used for home appliances, remote controllers, large-scale screen boards, etc.
In general, users manually manipulate a switch connected to a lighting apparatus through a cable in order to turn on or off the lighting apparatus. In this case, the patient, the senior citizen or the infirm who cannot move freely, or children who cannot reach the switch may feel inconvenience when turning on or off the lighting apparatus.
Recently, in order to solve the inconvenience, a lighting apparatus, which is turned on or turn off and can adjust lighting intensity by using a remote controller, has been launched in the market.
As the lighting and communication markets have been diversified, the requirement for the selective control of the characteristics (color temperature, dimming value, or brightness) of the lighting apparatus, or the selection of a communication scheme based on the speed/distance/power consumption among various communication schemes such as ZigBee, WiFi, or Bluetooth is increased.
In addition, since the communication module of receiving, processing and transmitting a user command is integrated with the light apparatus, when a power supply unit, an LED, a general lighting device and/or a control unit in the lighting apparatus are/is out of order, the lighting apparatus including the communication module must be exchanged.
An LED light source having high brightness has been used for lighting lamps. In addition, the LED light source has high energy efficiency and long life cycle so that the replacement cost is low. Further, the LED light source has superior durability against vibration or shock, and does not use a hazardous substance such as mercury, so the incandescent lamps or fluorescent lamps have been replaced with LED light sources for energy-saving, environmental protection and cost reduction.
Further, LEDs are useful for light sources of middle or large sized LCD televisions and monitors. The LEDs have superior color purity and low power consumption and can be easily miniaturized as compared with cold cathode fluorescent lamps (CCFLs) mainly used for light sources of the liquid crystal displays (LCDs). Thus, the products employing the LEDs are mass-produced, and also, researches on the LEDs are more actively conducted.
Recently, various technologies, which use a blue LED and reproduce white light using a quantum dot (QD) emitting red light and green light as a phosphor, are being developed because the white light reproduced by using the quantum dot has high brightness and superior color reproductivity.
Nevertheless, the need of researches for reducing light loss, which may occur in case where the LED is applied to LED backlight units, and improving color uniformity still arises.